Climate controversy spotlights ,

The Texas governor's views come in contrast with those of former Massachusetts Gov. Mitt Romney, an early front-runner in the GOP presidential field. Romney has said "I believe, based on what I read, that the world is getting warmer" and added that "I believe that humans contribute to that."

As a result, he said at a New Hampshire town hall meeting in June, "it's important for us to reduce our emissions of pollutants and greenhouse gases that may be significant contributors." However, he said any measures to stem greenhouse gases should be applied on an international basis. He opposed putting a carbon cap-and-trade system into place because it would put America at a competitive disadvantage.

The Perry vs. Romney climate split may be the latest and buzziest difference to emerge in the race for the GOP nomination, but when you look closely at the candidates, you'll see other differences as well. Here's a rundown on four of the leading candidates, related to four hot-button scientific topics: climate policy, evolution education, stem-cell research and science funding:

Climate policy:

We've already summarized Perry's and Romney's views.

U.S. Rep. Michele Bachmann of Minnesota opposes climate change legislation, saying that carbon dioxide is a "harmless gas." During a town hall meeting in South Carolina this week, she said that all the issues surrounding climate change would have to be "settled on the basis of real science, not manufactured science."

U.S. Rep. Ron Paul of Texas has called the concern about Earth's changing climate "the greatest hoax I think that has been around for many, many years, if not hundreds of years," based on the Climategate reports (see above). He's opposed to energy subsidies as well as government efforts to control greenhouse-gas emissions. "Pollution can be better taken care of under a private market system, under private property," he said.

(President Barack Obama, by the way, favors policies to reduce greenhouse-gas emissions, but the current "climate" in Congress has severely limited any progress on environmental initiatives.)

Evolution education:

Perry says he is a "firm believer in intelligent design as a matter of faith and intellect, and I believe it should be presented in schools alongside the theories of evolution." Intelligent design is the view that the complexity seen in nature is best explained as resulting from the efforts of an intelligent designer — for example, God, or an alien civilization. But in Perry's case, certainly God.

Romney said during his presidential campaign that he believes "God designed the universe" and that he believes God "used the process of evolution to create the human body." As Massachusetts governor, he opposed the teaching of intelligent design in public-school science classes. "The science class is where to teach evolution, or if there are any other scientific thoughts that need to be discussed," he told The New York Times. "If we're going to talk about more philosophical matters, like why it was created, and was there an intelligent designer behind it, that's for the religion class or philosophy class or social studies class."

Bachmann says "evolution has never been proven" and believes that intelligent design should be taught alongside the evolutionary view of biological change. "What I support is putting all science on the table and then letting students decide," Bachmann told reporters at the Republican Leadership Conference in New Orleans in June.

Paul says "nobody has concrete proof" for evo